PH Theory: Applied To Proper Hardware Selection
PH Theory: Applied To Proper Hardware Selection
PH Theory: Applied To Proper Hardware Selection
pH is a Unit of Measurement
• pH = Power of Hydrogen (H+)
• Defined as the Negative Logarithm of Hydrogen
Ion Activity
• pH = log (1/H+)
Used for Determining the Acidity or Alkalinity
of an Aqueous Solution
• Practical pH Scale for Industrial Instrumentation
• 0 - 14 pH
• HNO3 H+ + • KOH K+ -
+ OH
NO3-
+ -
• NH4OH NH4+ +
• HF H + F -
OH
4.0% NaOH
Crackers
Blood
Pure Water
Milk
Beer
Tomatoes
Oranges
Lemons
4.9 % H2SO4
0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0 13.0 14.0
pH
300
Base = Negative mV Signal
200 7.0 pH = 0 mV Output
100 Sensor Output Changes with
Temperature
mV
0
-100 • 0o C ~ 54.2 mV/pH
0
10
12
14
-200 • 25oC ~ 59.2 mV/pH
-300 • 50oC ~ 64.1 mV/pH
-400
Sensor Output is Corrected
-500
to 25oC with Automatic
pH
Temperature Compensation
0C 25C 50C
0
-0.2 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
-0.4
-0.6
-0.8
0C 10oC 20C 25C 30C 40C 50C
.1% H2SO4 98 0.02 1.8 1 0.347 0.816 0.572 0.755 2.161 0.335 0.675 1.976
Sulfuric
1% H2SO4 98 0.205 0.9 1.0051 3.49 8.2 5.75 7.59 21.72 3.36 6.78 19.86
Sulfuric
10% H2SO4 98 2.17 0 1.0661 37 87 61 80.5 230.4 35.7 71.9 210.6
Sulfuric
93% H2SO4 98 34.66 -1.1 1.8279 590.3 1386.9 972 1284.3 3674.1 568.6 1146.7 3358.4
Sulfuric
.1% HCL 36 0.027 1.6 1 0.467 1.097 0.769 1.016 2.906 0.45 0.907 2.657
Hydrochloric
1% HCL 36 0.275 0.7 1.0031 4.68 11 7.71 10.19 29.15 4.51 9.1 26.65
Hydrochloric
10% HCL 36 2.87 -0.4 1.0476 48.9 114.9 80.5 106.4 304.5 47.1 95 278.3
Hydrochloric
37% HCL 36 12.02 -1 1.185 204.7 481 337.1 445.4 1274.2 197.2 397.7 1164.7
Hydrochloric
1% HNO3 63 0.159 0.9 1.0037 2.71 6.37 4.47 5.9 16.88 2.61 5.27 15.43
Nitric
70% HNO3 63 15.7 1.4134 267.4 628.1 440.2 581.6 1664 257.5 519.3 1521
Nitric
1% H3PO4 98 0.307 1 1.0038 5.23 12.29 8.62 11.38 32.57 5.04 10.17 29.77
Phosphoric
85% H3PO4 98 43.84 1.685 746.7 1754.2 1229.4 1624.3 4647.1 719.2 1450.4 4247.8
Phosphoric
1% Acetic 60 0.166 2.8 0.9996 2.83 6.66 4.67 6.17 17.64 2.73 5.51 16.13
CH3COOH
100% Acetic 60 17.45 1.2 1.0477 297.1 698.1 489.2 646.4 1849.2 286.2 577.2 1690.3
CH3COOH
14
13
12
11
10
9
8
pH
7
6
5
4
3
2
1
0
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2 2.1
Base Addition
8.00
7.00
6.00
5.00
4.00
3.00
2.00
1.00
0.00
8.00
7.00
6.00
5.00
4.00
3.00
2.00
1.00
0.00